U.S. stocks traded slightly higher on Wednesday, paring better gains earlier after crude-oil prices headed south. Trade has been cautious a day before potentially market-moving events that have preoccupied investors' minds since the start of the week.

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The Dow Jones Industrial Average rose 15 points, or less than 0.1%, to 21,150. The S&P 500 added 2 points, or 0.1%, to 2,431. The Nasdaq Composite Index added 19 points to 6,294, up 0.3%.

Still, investors are focused on the so-called "Super Thursday" trio events: testimony on alleged Russian interference in the 2016 U.S. presidential election from former Federal Bureau of Investigation Director James Comey, the U.K. general election and a European Central Bank meeting.

Major indexes declined for two consecutive sessions amid concerns over these events. However, they remain close to record levels hit last week.

"No one wants to make big moves ahead of these events. And since we don't even have much economic data to trade off of, trading should be pretty quiet. We'll just be floating around," said Brent Schutte, chief investment strategist at Northwestern Mutual Wealth Management.

The big question regarding Comey is whether the ex-FBI chief will accuse President Donald Trump of abusing his power to derail an FBI investigation and whether there is any indication of potential links between Russia and Trump's election campaign, Sayed said. Any surprises in that testimony (http://www.marketwatch.com/story/what-to-watch-when-james-comey-testifies-to-the-senate-on-thursday-2017-06-05) to a Senate committee will be reflected in financial markets.

Schutte added that while Thursday's events could lead to elevated volatility in the short-term, they were unlikely to markedly change the tone on Wall Street. "It doesn't appear that a huge amount of new information will come out, so while these factors could move us in the short term, they won't matter over longer-time horizons," he said.

Meanwhile, technology shares were the biggest gainers of the day, extending a trend that has been seen throughout the year. The sector (XLK) rose 0.4%, with Apple Inc. (AAPL) up 0.7%.

Opinion: This 88-year-old stock market indicator is saying you can relax for now (http://www.marketwatch.com/story/this-88-year-old-stock-market-indicator-is-saying-you-can-relax-for-now-2017-06-06)

Geopolitics and economy: The only top-tier economic update on the calendar for Wednesday is a reading on consumer credit in April, due at 3 p.m. Eastern Time.

One focus is the run-up to the U.K. general election. While voters head to the polls Thursday, the outcome will likely not be known until Friday morning London time.

Opinion polls mostly indicate a victory for Prime Minister Theresa May's Conservative Party, but there are signs it could be a neck-and-neck race with the opposition Labour Party. An unexpected result could trigger volatility across Europe, spilling over to U.S. markets.

Read:5 things to know about the U.K. general election this week (http://www.marketwatch.com/story/5-things-to-know-about-the-uk-general-election-next-week-2017-06-01)

And check out: Watch for a shake-up among U.K. stocks after Thursday's election (http://www.marketwatch.com/story/watch-for-a-shake-up-among-uk-stocks-after-thursdays-election-2017-06-06)

No change in monetary policy is expected from the ECB meeting, but President Mario Draghi's comments will be scrutinized for signs the central bank is preparing to wind down its ultraloose monetary policy (http://www.marketwatch.com/story/draghis-ecb-may-take-baby-steps-toward-ending-ultraloose-monetary-policy-2017-06-06). The euro weakened on a report that the ECB may be ready to cut its inflation forecast through 2019 (http://www.marketwatch.com/story/euro-slumps-after-report-ecb-will-cut-inflation-outlook-through-2019-2017-06-07).

Other markets: European stocks were a mixed bag (http://www.marketwatch.com/story/european-stocks-rise-with-bank-stocks-up-as-santander-scoops-up-popular-2017-06-07), with the FTSE 100 (http://www.marketwatch.com/story/ftse-100-turns-higher-as-home-builders-get-a-boost-2017-06-07) slightly firmer, but the German DAX 30 index moving lower. In Asia , Chinese stocks rose 1.2%, bucking a retreat across most other indexes (http://www.marketwatch.com/story/china-stocks-rise-bucking-asian-market-retreats-2017-06-06).

Oil prices (http://www.marketwatch.com/story/oil-prices-pull-back-ahead-of-us-inventory-data-2017-06-07) turned sharply lower after U.S. supply data from the Energy Information Administration showed a rise of crude-oil inventories by 3.3 million barrels, greater than expected. Gold prices were modestly lower, and the dollar was trading flat, after showing firmer gains, the currency was gaining against the euro, which fell after reports that the ECB will cut its inflation outlook.